Propeller



C. H. HAVILL mm3, mi@

PROPELLER 2 Sheets-Sheet l Filed April 17, 1930 Suucntor wiwg Gttomcg c.H. HAVHLL 1,846256 PROPELLER Filed April 17, mso 2 shea-msnen 2 Feh 23,1932.

|Th4 .y l fedllli ,w y J Il 1/ 1 @Home 1 1 Patented F el). 23, 1932UNITED STATES PATENT OFFICE CLINTON H. HAVILL, OF SOUTH ORANGE, NEWJERSEY, ASSIGNOB- T ECLIPSE AVIA- TION CORPORATION, OF EAST ORANGE, NEWJERSEY, A CORPORATION OF NEW JERSEY PROPELLER Application led April 17,

This invention relates to propellers, and more particularly topropellers of the type adaptable for use on aircraft.

Aircraft propellers of the wooden type heretofore provided have, for themost part, been characterized by structures wherein a hub portion isintegral with the blades, the propeller being secured to the engineshaft by means of a special type of hub utilizing a plurality of boltsthat pass through the propeller. However, in certain instances, as forexample, installations wherein the pitch of the propeller blades may bevaried during` Hight, it has been necessary to employ separate woodblades fitted with specially formed metal sleeves that are adapted to beembraced by a hub drivably connected with the engine. It is desirable inmany instances to employ wood propellers of the last mentionedA type,yet the problems relating to the design of such propellers have alwayspresented serious difficulties primarily because of the low shearingstrength of the blade root, and the consequent danger of shearing of theblade from the hub at a point where the blade root enters the socket.

It is accordingly one of the objects of the present invention to providea propeller of the non-metal type and comprising a plu rality lofseparate blades which is so constructed as to overcome the difficultiesreferred to above.

Another object of the invention is to provide a novel wood propellerblade interiorly reinforced in such a manner as to secure increasedstrength and durability together with lightness in weight.

A further object is to provide a propeller blade having novel internalreinforcing members adapted to be placed under initial tension duringassembly of the blade.

Still another object is to provide, in a wood propel-ler, a-plurality ofmetal reinforcing members. the initial tension of which may beadjusted'to such a value that the fibre stress in thel wood, duringoperation of the propeller, will be within a safe workinglimit.

A still further object is to provide in a propeller, a blade built up ofa plurality of 1930. Serial No. 445,134.

wood laminations and metal reinforcing members, together with a novelroot structure.

The above and other objects will appear more ifully from the detaileddescription which follows when taken in connection with the accompanyingdrawings. One embodiment of the invention is illustrated in the drawingsbut it is to be expressely understood that the latter are employed forpurposes of illustration only and are not designed as a definition ofthe limits of the invention, reference being had for this purpose to theappended claims.

In the drawings wherein like reference characters refer to like partsthroughout the several views,

Figs. l and 1fL are vertical longitudinal sectional views of a propellerblade constructed in accordance with the presentin-` vention;

Figs. 2 and 2a are horizontal longitudinal sectional views of the bladeshown in Figs. 1 and la;

Figs. 3 and 4 are sections taken on lines 3-8 and 4-4respectively ofFig. 2;

Fig. 5 is a section of the blade taken on line 5-5 of Fig. 2a; and

Fig. 6 is a drawn out perspective of some of the parts adjacent the rootend of the blade.

Referring to the drawings and more particularly to Figs. l and la, apropeller blade embodying the principles of the present invention isillustrated as comprising a blade .indicated generally at 7, the rootend of which is adaptedto be received by a sleeve or socket 8 having anexterior contour similar to the sleeves or sockets employed with metalblades and which sleeves may be embraced by a split hub of well-knowndesign.`

The propeller blade 7 preferably comprises a plurality ofmetalreinforcing members or laminations to which the usual wood laminationsare secured in a manner to be more specifically pointed out hereinafter.As shown, a metal plate 9, extending substantially the full length ofthe blade has secured to either side thereof as by rivets l0, apair ofwood laminations 11 and 12 extending the entire width, of the blade,Fig. 5, there being provided a filler lamination 13 between the eX-terior contour of plate 9 and the perimeter of the blade in order tosecure a uniform thickness.

Each of the laminations 11 and 12 are channeled or grooved, Fig. 5, inorder to accommodate a series of reinforcing members such as wires 14.In the form shown, such reinforcing members are constituted by a singlewire, one end of which may be fastened 11nder a rivet 15, Fig. 2, andlooped successively through slots 16 and 17 provided in member 9 and abolt member 18 respectively. The last named member is positionedadjacent the root end of the blade in the gap formed by the spaced ends19 and 2O of member 9 and laminations 11 and 12 and is also providedwith slots 21 and 22 which are adapted to receive the looped ends of thewire 14 in connection with slots 23 and 24 in the member 9. It ispointed out that each of the laminations 11 and 12 are provided withslots adapted to register with the slots 16, 23 and 24 in order topermit the threading of wire 14 therethrough. After the winding of thewire has been completed theend is fastened beneath a rivet 24a, Fig.2. Aplurality of Y half round iller blocks 25 may be placed within each ofthe above-mentioned slots, if desired, in order to prevent any sharpbends in the loops of wire 4.

On either side of laminations 11 and 12, additional wood laminations 26and 27 are disposed, each of these last named laminations havingembedded therein, in order to form a flat surface, a pair of reinforcingplates 28 and 29 of unequal length and preferably secured together byany suitable means such as lspot welding. lThese plates may be attachedto the laminations as by means of screws 30. In accordance with wellknown practice, each of the laminations above referred to, is coatedwith a. layer of suitable adhesive before being pressed together.

Also embedded within laminations 26 and 27 and secured thereto as bymeans of screws 31, are metal plates 32 and 33 respectively, of lesslength than the reinforcing plates referred to heretofore. The propellerblade may thereafter be built up with further laminations 34, 35, 36 and37 and the root end of the resultant structure turned down to the propershape and size by methods and means well known in the art.

Means are provided for renderingthe contour of the rootend of the bladesuch that the blade may be secured in the usual type of split hub andpreferably there is associated therewith, means for placing the wires 14nr.- der initial tension and the other reinforc-y ing members orlaminations under initial compression. ln the form of the inventionillustrated, the first means referred 'to above is constituted by thesocket or sleeve 8 which is slipped over the turned down root end of theblade. A plug washer 38 is fitted into the end of the sleeve and theparts are secured in place by means of a nut 39 adjustably threaded onthe protruding end of the bolt 18. It is here pointed out that as thenut 39 is tightened, the bolt 18 will move to the left, as viewed inFig. 2, thus simultaneously placing the wires 14 under tension andforcing the root end of the blade securely within the sleeve. By placingthe wires 14 under tension it will be seen that the other metalreinforcing plates within the propel-v ler will be placed under yaninitial compression which will ensure the tension load due tocentrifugal force, during rotation of the propeller, to be first takenby the reinforcing members.

After the tension and compression of the internal members has beenadjusted to a suitable value, the sleeve 8 and root end of the blade aredrilled for the reception of shear bolts 40, 41, 42 and 43 which serveto securely maintain the parts in assembled position.- The nut 39 maynow be tightened without affecting the initial tension and compressionexisting in the reinforcing members and may be locked in position by anysuitable means. After the blade has thus been completely assembled theexternal contour thereof may be cut to the desired blade shape in anysuitable manner, and may be coated with metal as by spraying orelectro-deposition, if desired.

There is thus provided by the present invention a wood propeller bladeof novel construction wherein the constituent parts of the bla-de areassembled in such a manner as to result in a blade of increased strengthand durability and yet possessing the chief advantage of wooden typepropellers, namely, lightness in weight. By employing the internalstrengthening members under initial tension and compression, the bladeis rendered capable of use with the usual type of sleeve or socketutiliz-ed with metal blades, so that propeller blades constructed inaccordance with the present invention may be readily substituted for thepresent type of metal blades. The internal reinforcing members moreoversufficiently strengthen the blade, especially adjacent the root end,that all danger of the blade shearing olf Where the same enters the hubsleeve is substantially eliminated. lt is here pointed out thatbyinitially placing the internal supporting members under initialcompression, the latter will take a portion of the tension load due tocentrifugal force during operation of the propeller, thus relieving thewood portions of the blades of a portion of the tension load which wouldbe borne by such portions were the internal members omitted. By thisarrangement a propeller having such reinforced blades may be operated athigh speeds without increasing the stress in the libres of the Woodportions thereof to a dangerously high means for securing said blade andmembers value.

Though there has been illustrated and described only one embodiment ofthe invention, it is to be understood that the same is not limitedthereto but may be embodied in various constructional forms. Forexample, small metal rods may be substituted for the reinforcing Wires,or a plurality of internal Wires may be employed instead of the singlewire illustrated. While reference has been made in several instancesthroughout the description that the interior reinforcing members and themeans for applying compression to same may be particularly adaptable topropeller blades ofthe Wood type, it' is to be understood that thesemembers may also be employed in propeller blades made of metal or othersuitable material and which may be either solid or hollow. Various otherchanges may be made in the manner of constructing and arranging thecomponent parts of the propeller blade as Will now be apparent to thoseskilled in the art Without departing from the spirit of the invention.Reference will therefore be had to the appended claims for a definitionof the limits thereof.

"What is claimed is:

1. A Wood propeller blade having interiorly disposed metal reinforcingmembers, said members being of variable length, and means comprising aplurality of tension members for initially causing a compression in saidreinforcing members.

2. A solid propeller having internal mem bers initially under tension,and a plurality of internal reinforcing members initially incompression.

3. A propeller blade having a plurality of tension members, and meansincluding a threaded single member for adjusting the tension of all ofsaid first named members.

Il. Il propeller blade comprising a plurality of wood laminations, aplurality of looped members disposed interiorly of said blade,

and means including a single member for placing all of said membersunder initial tension.

5. A device of the class described comprising in combination a.plurality of Wood laminations, a metal reinforcing member disposedbetween tivo of said Wood laminations, and means for placing said metalmember initially in compression.

6. A Wood propeller blade comprising in combination a plurality of Woodlaminations, metal reinforcing members located between some of saidlaminations, a metal sleeve for receiving the root lend of said blade,and means for securing said laminations and said members to said sleeve.

7. A wood propeller blade having a plurality of internal reinforcingmembers under initial compression, a metal sleeve adaptled to receivethe root end of said blade, and

to said sleeve.

8. A propeller blade comprising in combination a plurality oflaminations, reinforcing members located between some of saidlaminations, a sleeve for receiving the root end of said blade, meansfor placing said reinforcing members initially in compression, and meansfor securing the reinforcing members to said sleeve.

9. A propeller blade comprising in combination a plurality of Woodlaminations, a plurality of metal reinforcing members, a metal sleevefor receiving the root end of said blade, means associated with saidsleeve for placing said reinforcing members under initial compression,and means for securing said laminations and reinforcing members to saidsleeve.

10. A propeller comprising in combination a Wood blade, a plurality ofmetal reinforcing plates disposed interiorly of said blade, a metalsleeve, and means for securing said blade in said sleeve.

11. In a propeller blade, a longitudinally extending internal membersecured to said blade at spaced intervals, a sleeve for receiving theroot end of said blade, a member extending into said sleeve andadjustably secured thereto, a plurality of looped membersinterconnecting said first and seeond named members, and means foradjusting said second named member to place said looped members undertension.

12. In combination With a propeller blade, a tension member disposedinteriorly ofsaid blade and secured thereto, a sleeve, and common meansfor drawing the rootend of said blade into said sleeve and for placingsaid member under tension.

13. A propellerl having a Wood blade, a metal sleeve, an internalreinforcing plate eX- tending substantially throughout the length ofsaid blade, means for connecting said blade yand plate at spacedintervals and means for securing the root end of said blade in saidsleeve.

14. The method of constructing a propeller blade of the type having acentral reinforcing member which comprises laminating the central memberon either side thereof, apply-v ing a. force in tension to effectcompression of said central member, connecting the central member andlaminations While maintaining the tension force and shaping the exteriorcontour of the blade.

15. In a Wood propeller blade having an internal reinforcing member anda sleeve adapted to receive the root end of the blade, the method whichcomprises, applying a force in tension to eifect compression in theinternal member and securing the root end of the blade Within saidsleeve While maintaining said tension.

16. In a laminated Wood propeller blade, a plurality of interiorlydisposed metal plates,

a plurality of Wires operatively connected with one of said platesintermediate its ends, a sleeve for receiving the root end of the blade,and a member Aassociated with said sleeve for adjusting the initialtension lof all of said Wires.

17. In a propeller blade having a hollow root portion, a plurality oftension members the outer end portions of which are operativelyconnected With the blade, a member disposed in said hollow root portionfor securing the inner end portions of said tension members, and meansassociated With said member for varying the axial position thereof toadjust the initial tension of allI of said tension members.

In testimony whereof I have signed this specification.

CLINTON H; HAVILL.

